(1) Field of the Invention
The present invention relates to a process for preparing resorcin by acid decomposition of meta-diisopropylbenzene dihydroperoxide (hereinafter referred to "m-DHP"). More particularly, the invention relates to a process for preparing resorcin in a high yield by conducting this decomposition reaction in the presence of a specific amount of water.
(2) Description of the Prior Art
A process for preparing phenols and ketones by acid decomposition of hydroperoxides of tertiary-alkylbenzenes has been known from old. Also a process for preparing resorcinol from meta-diisopropylbenzene dihydroperoxide (.alpha.,.alpha.,.alpha.',.alpha.'-tetramethylxylyl dihydroperoxide) is disclosed in, for example, the specification of U.S. Pat. No. 3,305,590 to Pollitzer et al. Further, various catalysts for this reaction have been proposed, and in the above specification, it is disclosed that a synthetic silica-alumina catalyst is used.
In the preparation of resorcin by acid decomposition of m-DHP, side reactions are caused more readily than in case of acid decomposition of other hydroperoxides of tertiary-alkylbenzenes. Accordingly, it is difficult to obtain resorcin in a high yield. For example, under ordinary acid decomposition conditions, reaction between resulting phenols and ketones is hardly caused to occur and the side reaction can be substantially neglected. On the other hand, since resorcin is more highly reactive than other phenols, it readily forms a condensation product with acetone. Further, resorcin readily reacts with carbinols or olefins formed as by-products to form high-boiling-point products. Therefore, according to the conventional processes, it is very difficult to prepare resorcin in a high yield by acid decomposition of m-DHP.
In general, m-DHP is prepared by liquid phase air oxidation of m-diisopropylbenzene (M-DIPB) and/or m-diisopropylbenzene monohydroperoxide (m-MHP). If m-DHP can be subjected to acid decomposition not in the completely pure state but in the state containing small amounts of other oxidation products, the expenses required for separation and purification of m-DHP will be saved or reduced and the production of resorcin will be performed industrially advantageously. However, according to the conventional techniques, it is more difficult to obtain resorcin in a high yield when such impure m-DHP is employed.